1. Technical Field
The present invention relates to control devices, display devices and methods for controlling a display device.
2. Related Art
As display devices for displaying images, electrophoretic type display devices using microcapsules are known. Those of active matrix type among the display devices are provided with a plurality of scanning lines extending in a row direction, a plurality of data lines extending in a column direction, and driving circuits for driving the microcapsules provided respectively at intersections between the scanning lines and the data lines. Upon application of a voltage to the scanning lines and the data lines, a potential difference is generated between electrodes provided on the driving circuits and counter electrodes disposed opposite to the electrodes through the microcapsules. As the potential difference is generated between the electrodes opposite to one another through the microcapsules, white particles and black particles within the microcapsules migrate according to the electric field caused by the potential difference. As the optical reflection characteristic changes due to changes in distribution of the white particles and the black particles within each of the microcapsules, images are displayed.
In some of the electrophoretic type display devices, at the time of changing a display image with the active matrix system, rewriting of the image may require multiple frames. However, if the image rewiring is started over the entire area when the image is rewritten across multiple frames, new data cannot be written until after the current writing is completed, such that addition or deletion of an image needs to be started after the image writing is once completed, which is time consuming and is therefore problematical in view of the operability. In order to address such a problem, JP-A-2009-251615 describes a system that executes rewriting by performing pipeline processing in the unit of a partial region. According to the system described in JP-A-2009-251615, an image is written in two partial regions that do not mutually overlap each other on the screen at timings shifted from one another. Even writing of one of the partial regions in which writing started earlier has not been completed, it is possible to start writing of the other partial region in which writing is to be started later, which results in an improved display speed, compared to other devices that do not use the system described above.
Incidentally, in the active matrix system, data lines function as capacitors due to their parasitic capacitances. Therefore, when the display operation requires a change in voltage on the data lines each time the scanning lines are selected, such a display operation leads to large power consumption. Therefore, when scanning operations with such large power consumption continue at the time of rewriting images, the power consumption may momentarily exceed the power supply limit of the power supply circuit. Further, in the active matrix system, driving circuits to provide currents increase as the display resolution is increased, which leads to greater power consumption.